Nuclear level densities and γ-ray strength functions of 180,181Ta and neutron capture cross sections

K L Malatji ,M Wiedeking,F Giacoppo,M Klintefjord,A C Larsen ,V W Ingeberg ,A Görgen ,F L Bello Garrote ,B V Kheswa ,K Hadyńska-Klȩk ,T Renstrøm ,T W Hagen ,D L Bleuel ,G M Tveten ,H T Nyhus ,E Šahin ,S Siem ,M Guttormsen ,C.p Brits ,S J Rose ,F Zeiser

doi:10.1051/epjconf/201714601010

K L Malatji , M Wiedeking + Show 19 more

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The γ-ray strength functions and nuclear level densities in the quasi-continuum of 180,181 Ta are extracted from particle-γ coincidence events with the Oslo Method, below the S n . The data were used as input in the TALYS reaction code for calculations of the astrophysical Maxwellian-averaged (n ,γ) cross-sections to investigate nucleosynthesis of nature's rarest stable isotope 180 Ta.

Highlights

A small number of naturally occurring neutron-deficient nuclides with Z ≥ 34 referred to as p-nuclei cannot be produced by stellar neutron-capture processes, while almost all p-nuclei with A > 110 are thought to be produced by the photodisintegration of s- and r -process seed nuclei
The particle-γ coincidence experiment was performed at the Oslo Cyclotron Laboratory (OCL) using 34 MeV 3He beam, with an average intensity of ≈2 nA, to populate excited states in 180,181Ta through the (3He,3He γ ) and c The Authors, published by EDP Sciences
The 180,181Ta γ -ray strength function (γ SF) show no pronounced features, except for the observed enhancement in the strength function from 6 MeV termed “Res2” resonance in 181Ta which may be related to E1 pygmy resonance

Summary

Introduction

A small number of naturally occurring neutron-deficient nuclides with Z ≥ 34 referred to as p-nuclei cannot be produced by stellar neutron-capture processes, while almost all p-nuclei with A > 110 are thought to be produced by the photodisintegration of s- and r -process seed nuclei. Calculations of the 180Ta production in the universe are often controversial since several processes, sometimes exclusively, could reproduce the observed 180Ta abundance in the cosmos, making it a interesting case to study. In the present case study, the 180,181Ta γ SF and NLD below the neutron separation energy, Sn, were investigated using the Oslo Method [8]. These results are used to determine the corresponding astrophysical Maxwellianaveraged (n, γ ) cross-sections (MACS) which in turn will be utilized in astrophysical network calculations to investigate nucleosynthesis of 180Ta. In Sect.

Experimental analysis and results

Findings

Discussion and future outlook